Buying ESCs

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25 July 2014 at 13:11 #5316
Looverlijn
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@looverlijn
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25 July 2014 at 13:11 #50656
Looverlijn
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@looverlijn
Has anybody had experience with these ESCs? I need 3 of the blighters for my new Italieri Schnellboot and at a tenner each they seem good value but are they any good?

Paul
25 July 2014 at 13:45 #50657
ashley needham
Participant
@ashleyneedham69188
Paul. good make, obviously forward only but should be fine.

May need to arrange a bit of airflow in the boat to keep cool, depending on the current your motors will be drawing.

Ashley
25 July 2014 at 14:19 #50659
Looverlijn
Participant
@looverlijn
Thanks Ashley,

I didn't realise there was no reverse (where does it define that?) I've just found out that the motors I've ordered are 385s rated 15 amps so thats the ESC I'm looking for. Would welcome your suggestions

Paul L
25 July 2014 at 18:38 #50670
ashley needham
Participant
@ashleyneedham69188
PL. I think you will find this is listed as an aircraft speed controller, hence no reverse and not much in the way of a heat sink..although some I have come with a stick-on one.

If you are not fussed about reverse and are not using too much power, these are fine and i have used a cuople (different makes) already. You do need to make sure bthey are set to the right battery and do not have a high voltage cutout. These are normally programmable and you need a program card, Not very expensive, worth their weight in gold. Ask Bob…oh, no perhaps DONT ask Bob!!

Ashley
25 July 2014 at 19:38 #50679
Empire Parkstone
Participant
@empireparkstone
I ran a schnellboot with 2x 385's and one mtronik 15A no probs other that too slow in process of changing to 2x 380's
26 July 2014 at 11:07 #50693
Malcolm Frary
Participant
@malcolmfrary95515
To figure out the required ESC you need to know what current your motor will take from your battery in reality rather than from a spec sheet which might have measurements taken in totally unrelated circumstances. Measure it under load, double the number, go for the next higher value ESC available, and that's your lad. Cautious derating like that ensures that the chosen ESC will survive boat use where they work harder for longer usually without the benefit of airflow cooling them. That, and avoiding ESCs with obviously extravagant claims regarding current handling.

The cost might be an upset, but performance costs, best to only spend it once.

Changing from 385s to 380s might take the single 15A ESC out of its comfort zone and eat into the safety margin. The increased performance will result in a higher current draw.
26 July 2014 at 11:32 #50695
Dave Milbourn
Participant
@davemilbourn48782
Paul
Your earlier post has some inconsistencies. A 380 motor has three poles and will spin at about 19000RPM on 7.2v unloaded i.e. it's a vicious little beast. Three of those in an Italieri MTB will make it fly but you mustn't run the motors at any more than 10A each or you'll be in danger of burning them out. The Turnigy ESC looks OK as long as you're happy with no reverse. In total contrast, the 385 is a 5-pole motor and generally runs on 12v, when it will spin at around 9000RPM unloaded. No way would it ever draw 15A unless you stalled it and three of those will make your MTB perform more like a narrow-boat.
I'd advise you to double-check what you've got before you go any further.
Dave M
26 July 2014 at 17:20 #50702
Looverlijn
Participant
@looverlijn
Thanks guys for all your input which has however raised more questions in my tiny mind . Now this is going to be a really dumb question but here goes anyway. I've already decided to use a P102 for the power side and will be using 2 x 7.2 volts as input and (this is not the really dumb question yet) do I also need to fit a battery sharing device such as P103 or can I just physically parallel them? Now the "really" dumb question – Do I actually need 3 ESCs of suitable rating for each motor or can I go with 1 high power ESC to drive all 3 motors. See I told you it was a dumb question?

Stands back and waits for a thorough flaming!
26 July 2014 at 19:04 #50707
Dave Milbourn
Participant
@davemilbourn48782
Paul
1. You can just physically parallel them, but you will have to make doubly sure that you discharge and recharge them for exactly the same times and hope that there isn't a slightly lame cell in one of the packs.
2. One ESC will do the job as long as it is rated at least three times that of one motor. If you do that then there's no point in using a P102.
(Now – did that hurt?)
Dave M
27 July 2014 at 09:34 #50731
Looverlijn
Participant
@looverlijn
Dave, I hardly felt that , not like when I used to be on a biker forum, those guys were really vicious. So it wasn't a completely dumb question then – Assuming I can find an ESC to fit the bill then as you say I could forget about the P102 but put in a P103 to take care of the batteries. Obviously my reason for posing the question in the first place was the relatively high cost of 3 ESCs but if the cost of the high power ESC comes out the same then the only saving to be made is not having to use the P102. Hey Ho we'll see what t'internet throws up.

Paul
27 July 2014 at 09:46 #50732
Dave Milbourn
Participant
@davemilbourn48782
Paul

Forget the Internet – buy one of these **LINK** You'll find nothing else comes near, especially for the price – and it's 100% British made.

Dave
29 July 2014 at 15:03 #50797
Looverlijn
Participant
@looverlijn
Getting a bit confused nwith some of the specs of various ESCs, in particular the quoted BEC output. It seems to vary from 4.5V up to 6V. What should the optimum voltage be for my Spektrum Rx? or is the quoted range OK for any Rx.

Paul
29 July 2014 at 16:48 #50800
Dave Milbourn
Participant
@davemilbourn48782
I've not yet met a receiver which wouldn't work on anything between 4.5v to 6v, and I've not yet encountered a BEC which puts out a voltage which is outside this range. Your Spektrum will be fine.
Dave M
29 July 2014 at 16:51 #50801
Looverlijn
Participant
@looverlijn
Thanks for the reassurance dave
30 July 2014 at 14:07 #50833
Looverlijn
Participant
@looverlijn
Got another dumb question

Things seem to be coming together now – Got 2 x 7.2 packs going through P103 then into P102 to give me 3 x motor outputs and 3 x ESCs for 3 x motors and then it struck me! 3 ESCs but only 1 RX input. What do I do now?

Paul
30 July 2014 at 15:50 #50835
Dave Milbourn
Participant
@davemilbourn48782
You need two Y-leads
30 July 2014 at 16:02 #50836
Looverlijn
Participant
@looverlijn
Y'know I had that in mind but thought "Nah it can't be that easy" so maybe I'm not as dumb as some would say. Thanks for being patient with me. As the saying goes "we are hot to trot/sail now"
30 July 2014 at 16:32 #50837
Dave Milbourn
Participant
@davemilbourn48782
Don't forget to disable the BECs in two of the speed controllers (assuming it's installed) by removing the red wire from the 3-wire plug. Chapter and verse in my August MB article, and my apologies for the title – it was a certain P Freshney's idea!

Dave M
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